Limit the bandwidth per IP or you could replace links with Jscript:
e.g.
replace
<a href="bigfile.zip">Foo</a>
with :
<script language="javascript">
<!--
document.write('<a h' + 're' + 'f="');
document.write('bigfile' + '.' + 'zip">');
// -->
</script>
Foo
</a>